103 lines
4.3 KiB
Markdown
103 lines
4.3 KiB
Markdown
Introduction to Inference Engine Device Query API {#openvino_docs_IE_DG_InferenceEngine_QueryAPI}
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===============================
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This section provides a high-level description of the process of querying of different device properties and configuration values.
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Refer to the [Hello Query Device Sample](../../inference-engine/samples/hello_query_device/README.md) sources and [Multi-Device Plugin guide](supported_plugins/MULTI.md) for example of using the Inference Engine Query API in user applications.
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## Using the Inference Engine Query API in Your Code
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The Inference Engine `Core` class provides the following API to query device information, set or get different device configuration properties:
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* <code>InferenceEngine::Core::GetAvailableDevices</code> - Provides a list of available devices. If there are more than one instance of a specific device, the devices are enumerated with `.suffix` where `suffix` is a unique string identifier. The device name can be passed to all methods of the `InferenceEngine::Core` class that work with devices, for example `InferenceEngine::Core::LoadNetwork`.
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* <code>InferenceEngine::Core::GetMetric</code> - Provides information about specific device.
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<code>InferenceEngine::Core::GetConfig</code> - Gets the current value of a specific configuration key.
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* <code>InferenceEngine::Core::SetConfig</code> - Sets a new value for the configuration key.
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The `InferenceEngine::ExecutableNetwork` class is also extended to support the Query API:
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* <code>InferenceEngine::ExecutableNetwork::GetMetric</code>
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* <code>InferenceEngine::ExecutableNetwork::GetConfig</code>
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* <code>InferenceEngine::ExecutableNetwork::SetConfig</code>
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## Query API in the Core Class
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### GetAvailableDevices
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```cpp
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InferenceEngine::Core core;
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std::vector<std::string> availableDevices = ie.GetAvailableDevices();
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```
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The function returns list of available devices, for example:
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```
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MYRIAD.1.2-ma2480
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MYRIAD.1.4-ma2480
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FPGA.0
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FPGA.1
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CPU
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GPU
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...
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```
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Each device name can then be passed to:
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* `InferenceEngine::Core::LoadNetwork` to load the network to a specific device.
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* `InferenceEngine::Core::GetMetric` to get common or device specific metrics.
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* All other methods of the `Core` class that accept `deviceName`.
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### GetConfig()
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The code below demonstrates how to understand whether `HETERO` device dumps `.dot` files with split graphs during the split stage:
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```cpp
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InferenceEngine::Core core;
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bool dumpDotFile = core.GetConfig("HETERO", HETERO_CONFIG_KEY(DUMP_GRAPH_DOT)).as<bool>();
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```
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For documentation about common configuration keys, refer to `ie_plugin_config.hpp`. Device specific configuration keys can be found in corresponding plugin folders.
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### GetMetric()
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* To extract device properties such as available device, device name, supported configuration keys, and others, use the `InferenceEngine::Core::GetMetric` method:
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```cpp
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InferenceEngine::Core core;
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std::string cpuDeviceName = core.GetMetric("GPU", METRIC_KEY(FULL_DEVICE_NAME)).as<std::string>();
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```
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A returned value looks as follows: `Intel(R) Core(TM) i7-8700 CPU @ 3.20GHz`.
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> **NOTE**: All metrics have specific type, which is specified during metric instantiation. The list of common device-agnostic metrics can be found in `ie_plugin_config.hpp`. Device specific metrics (for example, for `HDDL`, `MYRIAD` devices) can be found in corresponding plugin folders.
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## Query API in the ExecutableNetwork Class
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### GetMetric()
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The method is used to get executable network specific metric such as `METRIC_KEY(OPTIMAL_NUMBER_OF_INFER_REQUESTS)`:
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```cpp
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InferenceEngine::Core core;
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auto exeNetwork = core.LoadNetwork(network, "CPU");
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auto nireq = exeNetwork.GetMetric(METRIC_KEY(OPTIMAL_NUMBER_OF_INFER_REQUESTS)).as<unsigned int>();
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```
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Or the current temperature of `MYRIAD` device:
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```cpp
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InferenceEngine::Core core;
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auto exeNetwork = core.LoadNetwork(network, "MYRIAD");
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float temperature = exeNetwork.GetMetric(METRIC_KEY(DEVICE_THERMAL)).as<float>();
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```
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### GetConfig()
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The method is used to get information about configuration values the executable network has been created with:
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```cpp
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InferenceEngine::Core core;
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auto exeNetwork = core.LoadNetwork(network, "CPU");
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auto ncores = exeNetwork.GetConfig(PluginConfigParams::KEY_CPU_THREADS_NUM).as<std::string>();
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```
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### SetConfig()
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The only device that supports this method is [Multi-Device](supported_plugins/MULTI.md).
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